The present description generally relates to an image capturing process and device.
Almost every modern manufacturing process uses machine vision systems. These systems ensure fast, accurate and repeatable measurements, and thus guaranteeing a consistent product quality. A main component of machine vision systems is an image capturing camera apparatus comprising of a Charge Coupled Device (CCD) or a Complementary Metal Oxide Semiconductor (CMOS) image sensor. While there are many variations of image sensors, most of the cameras utilize interline transfer imaging sensors, which can be generally classed in three categories: area-scan, line-scan or Time-Delay Integration (TDI) devices. In web products that need to be scanned across a wide field of view at high-speed, line-scan sensors based cameras may be used. Line-scan sensors often consist of a single row of pixels (usually several thousand) that are exposed sequentially as the camera (or more often the object to be inspected) moves under the field of view of the camera. Since the integration time for such high-speed imaging needs to be short, high-brightness line-lights are used to illuminate the object as it passes under the field of view of the camera. In some very high-speed line-scan applications, however, even the brightest line-scan lights may not provide enough illumination and.
TDI images may be used to increase the responsivity of the imaging system. TDI imagers are a variant of single line line-scan devices that feature multiple rows (stages) of photo-sensors. As the image moves under the TDI array, each of the multiple rows shift charge to the adjacent row synchronously providing multiple exposures of the same scene, the final line-scan image when read from the imager will have a much higher sensitivity. TDI imagers have manufacturer preset integration stages and direction of integration. Furthermore, TDI imagers synchronize to a movement of an object being photographed.